PROJECT SUMMARY Diet and exercise interventions have made great strides in preventing and delaying T2D onset: benefits that surpass pharmacological interventions in some persons. Yet, variable responses from less intense, more affordable interventions and waning benefits over time are significant limitations. Identifying additional modifiable factors that can expand intervention options, beyond diet and exercise, are needed to reach heretofore resistant groups and to sustain metabolic benefits. One viable option is improving sleep. Multiple dimensions of sleep have been independently associated with T2D risk and poor glucose control in persons with T2D. Improved insulin sensitivity has been reported in a small community based daily sleep extension study (N= 16), as well as in a 2-day lab based sleep extension study using a personalized ?catch up? sleep intervention in healthy adults (N = 19,). Limited by small sample sizes, controlled lab conditions, and the exclusion of persons at greatest risk for T2D, the role of sleep in mitigating T2D risk remains uncertain. An important but unanswered question for tailoring sleep interventions is whether regular sleep timing should be prioritized. Given that irregular sleep-wake timing is widely prevalent, identifying the metabolic benefits or burdens of this sleep habit is critical. The proposed project in this K99/R00 award is a step toward independence in a program of research bridging circadian rhythms and metabolism to chrono-therapeutic interventions that mitigate type 2 diabetes (T2D) risk. Research: The study proposed in the K99 phase will leverage an existing data set to quantify the effects of irregular sleep timing on glucose regulation in persons with diabetes, prediabetes, and normoglycemia. This will elucidate individual differences in resiliency against or vulnerability to irregular sleep timing. Primary outcome measures will be hemoglobin A1c (for persons with diabetes and prediabetes) or insulin resistance (for persons with normoglycemia). The study proposed during the R00 phase will test the effects of a daily sleep extension intervention versus habitual sleep patterns on the percentage of time glucose is ? 140 mg/dL (n = 75 per group) in sleep restricted community-dwelling adults with pre-diabetes. Wearable sensor technologies (continuous glucose monitoring and accelerometry) will be used. This study will inform person- specific sleep interventions that improve glycemic responses, thus providing treatment for the prediabetic state. Training: To achieve overall career goals, the training plan will build upon the candidate's background in diabetes by affording her in-depth training in designing sleep interventions, wearable sensor technologies (specifically continuous glucose monitoring), and the analysis of large amounts of real time data. This training will also incorporate advancing her skills in writing and presenting scientific findings, as well as the skills to become a leader in the scientific community. A variety of approaches will be used to achieve these goals including formal coursework and structured one-on-one mentorship.